Mersenne Digest Monday, April 12 1999 Volume 01 : Number 544
----------------------------------------------------------------------
Date: Sun, 11 Apr 1999 12:45:37 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
> >I had done some thinking on it, and wouldn't it be great if
> there were some
> >sort of "live update" feature, where it could upgrade itself when new
> >versions come out. That's pie in the sky and I remember discussing
> >previously how that wouldn't work for everyone - security
> issues, bandwidth
> >issues, etc. but perhaps if it were an option.
>
> This feature would have meant that V17 shift count bug would have cost
> the project more cpu years than it did. In my case, its impact is a
> little under 1 cpu year (one exponent in the 10.5M area) because most
> processors I'm running were at older versions.
Well, that is unfortunately true in this case, but that also means there
will be CPU years being wasted by folks still running v17 who haven't heard
the news yet. Either way, when a version is buggy, you lose. As long as it
was optional.
Further thinking points me in the direction that you could point each
primenet client to a local server somewhere to retrieve updates. I do that
for McAfee Antivirus on my network of about 2 dozen servers. Put the latest
DAT files on a shared directory and schedule the servers to check for
updates every day. When a new DAT comes out, I test it on my machine and if
it's good, I put it in that directory and the servers will update themselves
in no more than 24 hours automatically.
For Norton programs, there's the Live Update Admin Utility where you can put
Live Updates on a local server and point all the Norton programs there
instead of the Symantec site.
Things like that are really wonderful, and if you're the type who'd rather
stick with an older version unless you *need* to upgrade, you do have that
option as well.
> There is a publicly available service which checks for changes in
> web pages,
> and sends email when a checked page changes. I think Internet Explorer
> V5 supports some sort of favorite-page-change detection too.
IE4 and IE5 have that (probably Netscape too?), and I think the web site
that checks and sends emails is www.mindit.com.
> This combined with being able to remotely stop an NT service and deposit
> updated files from a batch procedure on one workstation makes managing
> large numbers of workstations practical and quick.
Remember, you're talking to a guy who installed thousands of instances of
NTPrime remotely, across 3 different states, in a matter of days (using
nothing more than 4NT batch files and RCMD/NETSVC programs from the resource
kit). But we won't go there. :-) I'm not saying it can't be done, but it'd
be so much easier with some sort of built-in method for self-updates.
> I would find a popup box a terrible nuisance, so I'd like an option
> to turn it off or on, with default off.
If it were an option, there should be a way for REALLY important alerts to
get through, so that anyone running v17 would have been alerted about the
bug even if normal alerting were turned off. Wouldn't you rather have some
exceptions get through, with the decision about what qualifies as
"exceptional" being made by George and/or Scott?
> The feature I'd like to see at some point is the LLtest code made dual-cpu
> aware, splitting the load so one cpu does one half of the run-length and
> the other cpu does the other half, so that the onboard and on-chip caches
> would be more efficiently used, and total working set smaller,
> and exponents completed more quickly. I have a dual-pentium 200 MMX that
isn't terribly
> fast when running two prime95 instances on exponents above 10^7. The
> performance on the dual-pentium or dual-ppro systems I have access to is,
> when running two instances, about 1.6 times that of running 1 instance.
> So there is some room for improvement. On this setup, there are
> 2 L1 caches,
> but one L2 cache being shared by two prime95 instances.
Amen. In fact, if it were possible to code it to split the work among
multiple CPU's in any way, then it *is* technically possible to have even
seperate machines work on the same number, though you'd be limited by the
network link speed.
Consider. If you had a chip with multiple FPU engines, couldn't you code
the program to take advantage of that? From there, it's only a small step
to using the FPU processors on *seperate* CPU's, and from there, given a
fast enough link, seperate CPU's on entirely different machines.
SMP in NT does provide for some nice code-sharing parts that could make it
easier, but I'll leave it to the programmers to decide if the idea has any
merit.
In your case, sharing a single L2 cache is probably why you're seeing a
performance hit. On the quad PPro's I have, I run 4 instances of NTPrime,
each with the affinity set to a particular CPU, and I get just about 4X the
performance of a single CPU. They're Compaq servers and the architecture of
them is lovely though...buffered memory, of course each PPro has it's own L2
cache and I think they're the 1MB L2 cache chips, but I'm not sure.
Speaking of cache sizes, how much faster would you expect Prime95 to run on
a Pentium III Xeon with 2MB L2 cache, as opposed to one with only 512K L2
cache?
Aaron
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Date: Sun, 11 Apr 1999 14:35:15 -0500
From: Ken Kriesel <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
At 12:45 PM 1999/04/11 -0600, Aaron Blosser wrote:
...
>IE4 and IE5 have that (probably Netscape too?), and I think the web site
>that checks and sends emails is www.mindit.com.
mindit.com is not the one I was thinking of; there's one based in a US
university (Dartmouth?).
>> This combined with being able to remotely stop an NT service and deposit
>> updated files from a batch procedure on one workstation makes managing
>> large numbers of workstations practical and quick.
>
>Remember, you're talking to a guy who installed thousands of instances of
>NTPrime remotely, across 3 different states, in a matter of days (using
>nothing more than 4NT batch files and RCMD/NETSVC programs from the resource
>kit). But we won't go there. :-) I'm not saying it can't be done, but it'd
>be so much easier with some sort of built-in method for self-updates.
I remember. It can be done with less (just what's built in to NTWS).
>> I would find a popup box a terrible nuisance, so I'd like an option
>> to turn it off or on, with default off.
>
>If it were an option, there should be a way for REALLY important alerts to
>get through, so that anyone running v17 would have been alerted about the
>bug even if normal alerting were turned off. Wouldn't you rather have some
>exceptions get through, with the decision about what qualifies as
>"exceptional" being made by George and/or Scott?
No. I would not want it popping up on each of my computers, requiring
a mouse click on each; too tedious. Email is sufficient.
A popup for each instance on each multiple-cpu system is really a nuisance.
Imagine if USWest had seen 2500 of those popups on the same day.
VIRUS!!! Lynch whoever's responsible!!
>> The feature I'd like to see at some point is the LLtest code made dual-cpu
>> aware
...
>Amen. In fact, if it were possible to code it to split the work among
>multiple CPU's in any way, then it *is* technically possible to have even
>seperate machines work on the same number, though you'd be limited by the
>network link speed.
I think even gigabit ethernet would be insufficient. Networking means
driver overhead. The point of doing it is to regain efficiency and
reduce total runtime of one exponent so it's small compared to the machine's
working lifetime, even for 8-digit exponents.
>Consider. If you had a chip with multiple FPU engines, couldn't you code
>the program to take advantage of that? From there, it's only a small step
>to using the FPU processors on *seperate* CPU's, and from there, given a
>fast enough link, seperate CPU's on entirely different machines.
Several big if's.
Factoring could easily be parallelized, since it consists of 16 passes.
And the total amount of data being transported is very small.
Ken
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Date: Sun, 11 Apr 1999 15:51:32 -0400
From: Saint D <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
At 12:45 4/11/99 -0600, Aaron Blosser wrote:
>
>Amen. In fact, if it were possible to code it to split the work among
>multiple CPU's in any way, then it *is* technically possible to have even
>seperate machines work on the same number, though you'd be limited by the
>network link speed.
>
>Consider. If you had a chip with multiple FPU engines, couldn't you code
>the program to take advantage of that? From there, it's only a small step
>to using the FPU processors on *seperate* CPU's, and from there, given a
>fast enough link, seperate CPU's on entirely different machines.
I have a feeling that, if he had the machines and the time, George would
have already coded these things. If "I" discover the first million-digit
prime and become eligible for some part of that $50,000 prize, I plan to
feed a portion of that back to George with the proviso that he buy himself
an Alpha machine and some sort of multiprocessor machine to further the
search efforts.
Kel
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Date: Sun, 11 Apr 1999 14:24:19 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
> Factoring could easily be parallelized, since it consists of 16 passes.
> And the total amount of data being transported is very small.
If so, someone build me a paralellized factoring program and I'll run it on
my quad CPU machines. :-) *If* that were to happen, would it be possible
to look for factors bigger than the current ~64bit numbers? Have it run
back and look for factors of the Mersenne numbers....
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Date: Sun, 11 Apr 1999 16:26:27 -0400
From: Paul Cuni <[EMAIL PROTECTED]>
Subject: Mersenne: seti@home
Just to let everyone know I'm now running seti@home beta and prime 95
together. It works well since seti@home can only run as a screen saver
since it sucks up memory and prime95 gets the slime cycles that are left
over.
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Date: Sun, 11 Apr 1999 18:44:22 -0400
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
At 02:24 PM 4/11/99 -0600, Aaron Blosser wrote:
>If so, someone build me a paralellized factoring program and I'll run it on
>my quad CPU machines. :-) *If* that were to happen, would it be possible
>to look for factors bigger than the current ~64bit numbers? Have it run
>back and look for factors of the Mersenne numbers....
There is little use for a paralleled version of this. The only advantage
is that if you wanted a quicker test of a single number. Throughput would
be as large or larger running 4 instances testing different numbers
compared to a 4-CPU parallel program working on one number at a time.
+----------------------------------------------------------+
| Jud McCranie [EMAIL PROTECTED] |
| |
| "317 is a prime, not because we think so, or because our |
| minds are shaped in one way rather than another, but |
| because it is so, because mathematical reality is built |
| that way." G. H. Hardy, A Mathematician's Apology, 1940 |
+----------------------------------------------------------+
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Date: Mon, 12 Apr 1999 02:10:18 -0500
From: Amy and Shane Sanford <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
>>> I would find a popup box a terrible nuisance, so I'd like an option
>>> to turn it off or on, with default off.
>>
>>If it were an option, there should be a way for REALLY important alerts to
>>get through, so that anyone running v17 would have been alerted about the
>>bug even if normal alerting were turned off. Wouldn't you rather have some
>>exceptions get through, with the decision about what qualifies as
>>"exceptional" being made by George and/or Scott?
>
>No. I would not want it popping up on each of my computers, requiring
>a mouse click on each; too tedious. Email is sufficient.
>A popup for each instance on each multiple-cpu system is really a nuisance.
>
>Imagine if USWest had seen 2500 of those popups on the same day.
>VIRUS!!! Lynch whoever's responsible!!
I agree that a mouse click for every instance would create more problems
than it would solved but I think the idea of some additional warning
mechanism has some possible merit. There are a number of less intrusive
options availible other than a message box which would REQUIRE user
interaction. For example, have the Icon in the system tray change color
and/or blink based upon the urgency of the update (some sort of code that
George could set on the primenet server). And/or as reminder the next time
Prime95 is unmaximized add a text message (or even a hyper-link to jump to
the download page) in the window that displays the current iteration count .
Shane
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Date: Mon, 12 Apr 1999 10:06:38 +0200 (MET DST)
From: "Benny.VanHoudt" <[EMAIL PROTECTED]>
Subject: Mersenne: prove
Hi Cyril,
The fact that there exists a period for your procedure (whatever the
number of digits might be) is rather easy.
Indeed, say you start with a n-digit number than after just a single
step you get another n-digit number and so on. As there are only
10^n n-digit numbers you always obtain a period of at most
10^n numbers.
You can get a smaller upper bound for the period because you
always re-order the digits in a decending order, thus the number of
ordered n-digit numbers is an upper bound for the period.
Benny
- --------------------------------------------------------------------
CYRIL WROTE:
>I''m searching a prove of a little problem.
>You take a four digit number where not all digits are equal such 5957 and
>reorder the digits
>such that the biggest digit is at the first place, the second at the second
>place etc.
>Then subtract the smallest possible reoredering from the the other number
>and restart the process.
>As result you will get 6174.
>
>Example: 5957
>
>9755-5579=4176; 7641-1467=6174; 7641-1467=6174
>
>If you take a five digit number, the result will be a period of 74943,
>62964, 71973, 83952.
>With six digits it will be a period too.
>Have anyone got a prove tor that?
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Date: Mon, 12 Apr 1999 10:05:19 GMT
From: "Brian J Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: rpcnet
James Griffin <[EMAIL PROTECTED]> writes:
> To stop Prime95 Ver 18 from crashing while not connected to the Internet, I
> have to use rcpnet.dll from Ver 17. I never had any problem until Ver 18.
Interesting. rpcnet.dll from the v18 distribution is much smaller than
that in the v17 distribution.
Should be safe enough to keep the v17 distribution copy.
Actually my systems are all using either http or the special
rpcnet.dll used to connect to the PrimeNet Proxy server, so I just
don't know how badly the v18 rpcnet.dll is broken.
Regards
Brian Beesley
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Date: Mon, 12 Apr 1999 11:32:49 +0000
From: "Steinar H . Gunderson" <[EMAIL PROTECTED]>
Subject: Mersenne: Really really crazy idea...
Just to add some life to this list... No, this is _not_ a joke. This is only
a really crazy idea.
We are always in search of more CPU power. Since toasters are not (yet)
powerful enough to run LL tests, I thought we might turn to the second
greatest mass of CPU power: consoles.
Those machines are ultra-powerful and usually off 20 hours a day (unless the
owner is really freaked)... Of course, there are a lot of problems associated
with this approach:
1. Getting somebody to code the program.
2. Getting the program over to the console. (Hasn't the N64 got support for
some kind of writable cartridges now? Not pirate cartridges, but some kind
of tape, I believe. At least it was advertised when the N64 was new.)
3. Getting the exponents to and from the console. (This could perhaps be
done manually, but saving some stuff such as LL residues while calcing
would be a _big_ problem. Perhaps there is a way to save in memory cards
or similar, like the PS. Or perhaps we should restrict them to factoring.)
As I said, this is pretty unrealistic for now, but certainly an interesting
opportunity if we can do it. At least it would generate a load of publicity...
/* Steinar */
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Date: Mon, 12 Apr 1999 12:28:23 +0100
From: "James Smith" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
> We are always in search of more CPU power. Since toasters are not (yet)
> powerful enough to run LL tests, I thought we might turn to the second
> greatest mass of CPU power: consoles.
// SNIP
> As I said, this is pretty unrealistic for now, but certainly an
interesting
> opportunity if we can do it. At least it would generate a load of
publicity...
Perhaps not so, with the SEGA Dreamcast and the Playstation 2 both planned
for release with modems this is almost a posibility in the near future.
- --
James Smith
[EMAIL PROTECTED]
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Date: Mon, 12 Apr 1999 12:38:30 +0100
From: "James Smith" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
> > We are always in search of more CPU power. Since toasters are not (yet)
> > powerful enough to run LL tests, I thought we might turn to the second
> > greatest mass of CPU power: consoles.
>
> // SNIP
>
> > As I said, this is pretty unrealistic for now, but certainly an
> interesting
> > opportunity if we can do it. At least it would generate a load of
> publicity...
>
> Perhaps not so, with the SEGA Dreamcast and the Playstation 2 both planned
> for release with modems this is almost a posibility in the near future.
Something else I forgot to mention, the Dreamcast runs Windows CE, so this
should be a fairly easy one to code for.
Plus the playstation 1 has parallel IO on the back for plugging "action
replay" type cartridges in to it, most of these have standard parallel type
connectors on for attaching to a PC for downloading Cheat codes to. There
should be some way of utilising this method for transferring code and
exponents to and from it. It would however mean manufacturing the cart's
for it, and there would obviously be cost implications in this.
see http://www.x-plorer.co.uk/ for details of a cart that already does this.
- --
James Smith
[EMAIL PROTECTED]
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Date: Mon, 12 Apr 1999 07:51:18 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: preventive measures
> >No. I would not want it popping up on each of my computers, requiring
> >a mouse click on each; too tedious. Email is sufficient.
> >A popup for each instance on each multiple-cpu system is really
> a nuisance.
> >
> >Imagine if USWest had seen 2500 of those popups on the same day.
> >VIRUS!!! Lynch whoever's responsible!!
Well, US WEST is trying to lynch me anyway, so... :-)
> I agree that a mouse click for every instance would create more problems
> than it would solved but I think the idea of some additional warning
> mechanism has some possible merit. There are a number of less intrusive
> options availible other than a message box which would REQUIRE user
> interaction. For example, have the Icon in the system tray change color
> and/or blink based upon the urgency of the update (some sort of code that
> George could set on the primenet server). And/or as reminder the
> next time
> Prime95 is unmaximized add a text message (or even a hyper-link to jump to
> the download page) in the window that displays the current
> iteration count .
Yes, actually that's more what I had in mind. I thought that maybe there
could be a little status bar at the bottom of the Prime95 window that
scrolls important information or something. I like the bit about having the
icon change color, but it's already mostly RED which would have been a good
"alert" color. Maybe slowly flashing YELLOW or something, or make is
usually GREEN then YELLOW for messages and RED for big problems.
For folks running this on a lot of machines, you'd obviously just turn this
feature off on most of them, only keeping it turned on for your own personal
machines.
Well, these are all good thoughts, let's see what George and Scott can
do...they've already done so much as it is.
Aaron
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Date: Mon, 12 Apr 1999 10:32:15 -0400
From: Joth Tupper <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Question & Suggestion
Message text written by "Brian J Beesley"
>Doesn't seem to make much difference to either of my P100
laptops. What *does* make a difference (a big one) is whether you
leave the screen and hard disk (especially the hard disk) running.
<
In my testing of battery life on my notebook, I was comparing several
fairly similar scenarios with the only difference I am sure of being
prime95
running or stopped.
For about 3 hours (each Saturday my older kid has a music rehearsal
which sets the time frame), I would work away at word documents or database
code or queries of a number of other tasks which would keep the screen
going
and use the hard drive often enough to keep it turned on.
My battery is the newer style without the memory effect. It is the base
battery
for the model notebook and is often good for 10 to 11 hours of working. I
found I
apparently needed to remove the PCMCIA cards when the unit is unplugged as
well as toggle a couple of BIOS settings for "Wake on..."
>The problem with my system is that the battery is NiMH, this has a
"memory effect", if it's in use on mains continuously then it seems
to run down quickly, whereas just after full discharge/recharge the
battery life is much longer.<
This was a concern I had for my batteries. In my case, once the charging
is at 100%,
charging stops and the battery is not further charged. According to the
manufacturer's (Micron)
tech support, leaving the unit plugged in or not should have no effect on
battery life (either in
the number of charges over its life or in the time to discharge).
I will be doing more testing but...
My P133 notebook had very little power awareness or control. This P-II
Micron GoBook2
uses many of the more recent features. I found that I really could get the
promised 10 or
11 hours of runtime use (I turned it off during idle times) from the base
battery
...I was only hoping for about half of this which would
still be a significant multiple of my old P133's battery life.
Then I noticed that the battery was running down in 2 to 3 hours, so I
tried to isolate the causes.
I found several things (noted above) before checking Prime95. Again, your
comments make me
want to recheck my conclusions but there are a number of differences among
the families of
Pentium and Pentium-II mobile processors. It may well be that each
notebook will need a test
to see if running/not running prime95 has a significant impact on battery
life.
One of the problems with a test is that older rechargeable batteries (with
memory effect) were often only
good for about 100 full charges. The newer batteries are supposedly good
for 375 (or so) full charges.
This means that a "test" carries a real cost to the life of the unit. By
comparison, the chips are expected
to last for 5 to 7 years (AMD, I think) up to 15 years (older Intel, not so
sure of the P-II, Celeron) so tests
that take a few days are not a very significant fraction of the life of the
CPU.
Joth
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Date: Mon, 12 Apr 1999 19:53:01 +0100
From: "James Smith" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: preventive measures
OK, I haven't been following this thread so this may have already been
mentioned and discarded, but how about some sort of "auto update" feature.
It could be turned on/off in the options and would enable people to run
almost unattended with updates coming either as and when required, or they
could be set to occur in tandem with an exponent update.
I appreciate that most software updates require the software to be stopped
during update then started again afterwards, but would it not be possible
for the update to update the required files to temporary ones, that replace
the old ones on the next reboot using win9x runonce facility in the
registry. e.g.. the updates being prime95.new etc. I know this means the
updates only happen at the reboot, but who can convince a win 9x machine to
run longer than 8 hours without one anyway? (off topic - have you seen the
"continuous running fix" for win98 yet? no joke, It fixes a bug that causes
the computer to lock up after 49.7 days. 49.7 days? I cant get mine to
last 49.7 hours!)
Another method would have to be found for updating the OS2 / Linux etc.
clients, but I am sure there must be one.
- --
James Smith
[EMAIL PROTECTED]
> Yes, actually that's more what I had in mind. I thought that maybe there
> could be a little status bar at the bottom of the Prime95 window that
> scrolls important information or something. I like the bit about having
the
> icon change color, but it's already mostly RED which would have been a
good
> "alert" color. Maybe slowly flashing YELLOW or something, or make is
> usually GREEN then YELLOW for messages and RED for big problems.
>
> For folks running this on a lot of machines, you'd obviously just turn
this
> feature off on most of them, only keeping it turned on for your own
personal
> machines.
>
> Well, these are all good thoughts, let's see what George and Scott can
> do...they've already done so much as it is.
>
> Aaron
>
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
>
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Date: Mon, 12 Apr 1999 21:00:15 +0200
From: "Floris Looyesteyn" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
>We are always in search of more CPU power. Since toasters are not (yet)
>powerful enough to run LL tests, I thought we might turn to the second
>greatest mass of CPU power: consoles.
If i remember right this was mentioned earlier on the list
People then said most consoles are really bad at
accurate floating point calculations because they aren't
used much in games.
something else:
I still believe we should make a mersenne virus which will let all
infected computer calculate mersenne primes.
unfortunately this would give a real bad name to GIMPS.
but lets hear your thought on this
Floris Looyesteyn ( who has to retest 2 7mil primes which were at 70%)
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Date: Mon, 12 Apr 1999 15:01:30 -0400
From: "Tim Charron" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Search for a prove
>Hi all,
>
>I''m searching a prove of a little problem.
>You take a four digit number where not all digits are equal such
>5957 and reorder the digits such that the biggest digit is at the
>first place, the second at the second place etc. Then subtract the
>smallest possible reoredering from the the other number and restart
>the process. As result you will get 6174.
>
>Example: 5957
>
>9755-5579=4176; 7641-1467=6174; 7641-1467=6174
>
>If you take a five digit number, the result will be a period of
>74943, 62964, 71973, 83952. With six digits it will be a period too.
>Have anyone got a prove tor that?
For a poor man's proof, I wrote a quick app to exhaustively search.
The results differ slightly from your assertion:
3 digit numbers: 495->495
4 digit numbers: 6174->6174
5 digit numbers:
96988 #s: 74943->62964->71973->83952->74943
3002 #s: 59994->53955->59994 (example: 16531)
6 digit numbers:
941993 #s: 851742->750843->830862->862632->642654->420876->851742
56181 #s: 631764 (example: 142486)
1816 #s: 549945 (example: 551616)
7 digit numbers:
9999990 #s: (all possible):
8649432->7519743->8429652->7619733->8439552->
7509843->9529641->8719722->8649432
8 digit numbers:
86326632->64326654->43208766->85317642->75308643->84308652->86308632
or
86526432->64308654->83208762
or
97508421
(I didn't let it finish, so don't have the counts of each sequence)
- -- Tim
Tim Charron
[EMAIL PROTECTED]
[EMAIL PROTECTED]
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Date: Mon, 12 Apr 1999 15:58:42 -0400
From: "Ernst W. Mayer" <[EMAIL PROTECTED]>
Subject: Mersenne: Laptop upgrade question
I have a question about porcessor upgrades for a laptop - at home
I run Prime95 on an Acer Extensa 600-series laptop, which came with
a 120MHz Pentium, and has been running overclocked (with extra cooling
fan) at 180MHz for the past year without problems.
My question is, what is the fastest processor I could install on the
same motherboard - am I at the limit already? And, is there a reasonably
inexpensive way to upgrade the MB if that is needed to install a faster
CPU?
Thanks,
Ernst
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Date: Mon, 12 Apr 1999 21:19:26 +0100
From: "James Smith" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
> People then said most consoles are really bad at
> accurate floating point calculations because they aren't
> used much in games.
Who said that? Floating point maths is used extensively in 3D calculation,
which all modern consoles excell at.
> I still believe we should make a mersenne virus which will let all
> infected computer calculate mersenne primes.
> unfortunately this would give a real bad name to GIMPS.
> but lets hear your thought on this
Nice idea! Unfortunately it would probably get GIMPS shut down.
- --
James Smith
[EMAIL PROTECTED]
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Date: Mon, 12 Apr 1999 21:24:33 -0000
From: [EMAIL PROTECTED]
Subject: Re: Mersenne: Really really crazy idea...
>> People then said most consoles are really bad at
>> accurate floating point calculations because they aren't
>> used much in games.
>
>Who said that? Floating point maths is used extensively in 3D calculation,
>which all modern consoles excell at.
.. but unfortunately only single-precision floating point is needed ... this is
really not much use (you will get, at best, only 5 or 6 bits per element using SP
floating-point arithmetic in a discrete weighted transform)
>> I still believe we should make a mersenne virus which will let all
>> infected computer calculate mersenne primes.
>> unfortunately this would give a real bad name to GIMPS.
>> but lets hear your thought on this
>
>Nice idea! Unfortunately it would probably get GIMPS shut down.
As a "network policeman" I should point out that I am under an obligation to
try to _prevent_ access by any site distributing material in this way. However
well-meaning the intentions are. On my own I couldn't shut down GIMPS, but a small
number of people like me could certainly make the PrimeNet server pretty well
useless.
Also, remarks like this make it hard for me to "sell" voluntary participation in
this, or any similar, project. It's already hard enough to explain to average
users that having Prime95 running on their system has no measurable effect on the
ability of their system to carry out its "proper" work & does not (in itself)
cause any significant increase in energy usage or "wear out" the system at an
accelerated rate.
If we thought that we could cope with the workload on the server, I'd seriously
suggest that we get talking to either Microsoft or the major PC vendors (Dell,
Gateway, Packard Bell etc) about incorporating Prime95 into the default software
distribution. But I'd want to be pretty damn sure that we could cope with
(potentially) tens of millions of active clients first.
Regards
Brian Beesley
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Date: Mon, 12 Apr 1999 17:48:44 -0400
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: Mersenne: [Mersenne] this setback
With this setback, does it still make sense for machines slower than P-133
to default to double checking, or should some of them go back to initial LL
tests?
+--------------------------------------------------------+
| Jud McCranie [EMAIL PROTECTED] |
| |
| 127*2^96744+1 is prime! (29,125 digits, Oct 20, 1998) |
+--------------------------------------------------------+
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Date: Mon, 12 Apr 1999 18:08:12 -0400
From: Peter Doherty <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
At 21:19 04/12/1999 +0100, you wrote:
>> People then said most consoles are really bad at
>> accurate floating point calculations because they aren't
>> used much in games.
>
>Who said that? Floating point maths is used extensively in 3D calculation,
>which all modern consoles excell at.
Yes, but I think it's a question of single precision vs. double precision.
The SSE or 3DNow! units of the K6-2 and P-3 can't be utilized by Prime95
because they are single precision only. Most games only use single
precision floating point calculations. The consoles are the same. Prime95
needs a double-precision unit to do it's complex calculations.
Overall I think the console idea is a really bad one.
- --Peter
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Date: Mon, 12 Apr 1999 15:31:59 -0700
From: Martin Lehmann <[EMAIL PROTECTED]>
Subject: Mersenne: Re: Mersenne Digest V1 #543
Did someone else notice that the top producers lists on mersenne.org and
entropia.com are inconsistent? Apparently, on mersenne.org the exponents
that were affected by the V17-bug are no longer taken into account.
Shouldn't this be dealt with consistently?
In case this has been explained in an earlier Mersenne Digest, my apologies.
Martin
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Date: Mon, 12 Apr 1999 18:42:36 -0400
From: Saint D <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Really really crazy idea...
At 21:24 4/12/99 -0000, [EMAIL PROTECTED] wrote:
>
>If we thought that we could cope with the workload on the server, I'd
seriously
>suggest that we get talking to either Microsoft or the major PC vendors
(Dell,
>Gateway, Packard Bell etc) about incorporating Prime95 into the default
software
>distribution. But I'd want to be pretty damn sure that we could cope with
>(potentially) tens of millions of active clients first.
Why not start a little smaller and see if we can get RedHat, Debian, SUSE,
and other Linux distributions to include mprime with their distributions?
Kel
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Date: Mon, 12 Apr 1999 18:30:21 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Really really crazy idea...
> > I still believe we should make a mersenne virus which will let all
> > infected computer calculate mersenne primes.
> > unfortunately this would give a real bad name to GIMPS.
> > but lets hear your thought on this
>
> Nice idea! Unfortunately it would probably get GIMPS shut down.
Personally, at this point, I would strongly discourage putting any GIMPS
software on any machine but your own unless you're 100% positive you have
permission to do so. It'll only cause grief, as well intentioned as it may
be (speaking from experience here). Some people just don't appreciate the
"art" of it I guess. :-)
Aaron
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Date: Mon, 12 Apr 1999 20:35:47 -0400
From: "Ernst W. Mayer" <[EMAIL PROTECTED]>
Subject: Mersenne: lucas_mayer V2.6 (Was: Request for Software)
John Gilmore writes:
>Anyone have an executable that runs under SGI Irix 6.5 I can use for
>double-checking and acquire via FTP or e-mail attachment?
The most recent version of my LL code, V2.6, has (Fortran-90) source code
and binaries for Alpha Unix and SGI Irix (the latter optimized for MIPS R10K).
Readme: ftp://nigel.mae.cwru.edu/pub/mayer/README
Source: ftp://nigel.mae.cwru.edu/pub/mayer/
Alpha binary: ftp://nigel.mae.cwru.edu/pub/mayer/bin/ALPHA_OSF/Mlucas_2.6X.exe.gz
(and ftp://nigel.mae.cwru.edu/pub/mayer/bin/ALPHA_OSF/libshpf.so.gz
if you lack an F90 compiler - this is the run-time library you need.)
SGI binary: ftp://nigel.mae.cwru.edu/pub/mayer/bin/SGI/Mlucas_2.6X.exe.gz
There are two major changes from V2.5:
1) Non-power-of-2 runlengths are here. The code supports FFT runlengths
of form {1,3,5,7)*2^n, i.e. the same lengths as George Woltman's Prime95.
2) More efficient FFT: the code now does a decimation-in-frequency forward
FFT and decimation-in-time inverse FFT, thus avoiding any bit-reversal data
reorderings.
The code allows exponents up to 20M, so can be used for double-checking or
current assignments.
NOTE: people upgrading from V2.5 will have to finish their current exponent
before switching to V2.6.
Here are some per-iteration timings for two slightly different MIPS R10K setups,
for exponents spanning the current double-checking and new testing ranges:
FFT length / max. exponent (in millions)
Platform 96K 112K 128K 160K 192K 224K 256K 320K 384K
1.99M 2.30M 2.62M 3.27M 3.91M 4.56M 5.20M 6.46M 7.71M
195 MHz R10K, .087s .104s .120s .159s .200s .244s .287s .399s .511s
32 KB D-cache
4MB L2 cache (One processor of a dual-processor Origin, run using runon 0)
250 MHz R10K, .108s .129s .145s .192s .233s .277s .311s .398s .481s
32 KB D-cache
1MB L2 cache (A single-processor Octane)
Note the salutary effect of having a nice large L2 cache - the 195MHz CPU
timings are better than the 250MHz up to FFT length 320K.
NOTE TO SPARC USERS: I finally know why my code sucks on SPARC - a crappy F90
compiler. Jason Papadopoulos was kind enough to look at the executable
produced by the SPARC F90 compiler. Here is his review:
"Your program is slow on the ultra because Sun's
F90 compiler does a miserable job. Even when you tell it to use the
Sparc V9 instruction set, to use 64-bit loads and stores, and to target
the ultra explicitly it still insists on using 32-bit loads and stores
almost exclusively. It also alternates loads and stores a lot, which
on the Ultra causes nasty bus-switching stalls. Finally, it has no
idea about loading values in advance; all your real*8 values are loaded
(one real*4 at a time) and then arithmetic is immediately performed on
them. At least it mixes integer and floating point nicely."
Sorry, SPARCers, you'll have to wait for the C version.
Happy hunting,
Ernst
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End of Mersenne Digest V1 #544
******************************
